Natural Temperature Regimes Research Articles

Результати отримання ікри від вперше дозрілих плідників осетра (Acipenser baerii Brandt, 1869), вирощених в індустріальних умовах

Purpose. To determine and evaluate productive parameters in the process of artificially obtaining ovulated eggs in different seasons from brood Siberian sturgeon Acipenser baerii Brandt, 1869 at first maturity grown in conditions of floating cage systems with a natural water temperature of the forest-steppe of Ukraine. Methodology. The material for the study were 65 individuals of age-8+ to 10+ sturgeon females with a body weight of 6.02‒8.64 kg firstly used in breeding works, which were grown using intensive technology in floating cages installed in a water body with a natural temperature regime of the forest-steppe zone. Experiments on obtaining mature eggs were conducted in non-traditional breeding periods — in winter (February) and at the end of spring (the last decade of May). In the winter, a recirculation aquaculture system was used with the use of special methods of preparing brood fish in the process of obtaining mature eggs. Collection of ovulated eggs was carried out with the preservation of life of brood fish after hormonal stimulation of gonad maturation using a carp pituitary preparation. Determination of productive parameters and study of physicochemical factors of the environment were carried out according to generally accepted methods. Findings. In different seasons of the year at a water temperature of 14–21°C, high efficiency of gonad maturation was registered in both groups of brood fish. The average weight of mature eggs obtained in separate groups of sturgeon females was 1.02–1.15 kg with an average gonadosomatic index of 13.92–15.42%. 94–97% of fish responded to pituitary stimulation in different groups of brood fish. The duration of brood fish maturation after the second (decisive) injection with a total dose of a gonadotropic substance of 3.5–4.0 mg/kg of fish weight varied within 14–25 hours. The survival rate of brood fish after egg collection was close to 94%. Originality. The results of obtaining mature eggs from Siberian sturgeon (Acipenser baerii) females at first maturity using the industrial fish farming technology, which is not common for aquaculture in Ukraine, were determined and analyzed. Practical value. The study results are of interest for the development of modern sturgeon aquaculture technologies in the conditions of industrial-type farms, primarily for the organization of caviar production. Keywords: brood sturgeon (Acipenser baerii), industrial fish farming, oocyte ovulation, productive parameters, caviar production.

Рибогосподарська оцінка плідників сибірського осетра (Acipenser baerii Brandt, 1869), вирощених у плавучих садках за природної температури води Лісостепу України

Purpose. To determine and evaluate the main fishery parameters in the process of artificial production of mature eggs from brood Siberian sturgeon grown in floating cages at natural water temperature of the Forest-Steppe of Ukraine. Methodology. The material for the study was 121 specimens of Siberian sturgeon females of various ages with body weights from 3.80 to 16.84 kg, which were cultivated in industrial-type farming conditions in a water body with a natural temperature regime for the Forest-Steppe zone Ukraine with the use of floating cage systems. Experiments on obtaining mature eggs were carried out under controlled water temperature during the period from January to April under the conditions of a recirculation aquaculture system. Hormonal stimulation for the maturation of sturgeon gonads was performed using natural cyprinid pituitary preparations. Determination of fishery indicators and study of environmental abiotic factors were carried out according to methods generally accepted in fish farming and hydrochemistry. Findings. The efficiency of maturation in brood fish of different groups varied between 57–100% at a water temperature of 14.0–15.5°C after the injection of a gonadotropic drug with a total dose from 2.5 to 4.5 mg/kg per fish weight. A total dose of the gonadotropic drug of 3.5 mg/kg per fish weight was found to be sufficient for the high efficiency of gonad maturation. The weight of mature eggs obtained from brood fish aged 8+ to 17+ varied on average from 0.54 to 2.12 kg. The average working fecundity and relative fecundity in females of different ages varied, respectively, within the range of 33.60-108.21 thousand eggs and 6.62-7.95 thousand eggss/kg of fish weight, with average values of the gonadosomatic index of 10.71-15.81%. Originality. The peculiarities of obtaining ovulated eggs and the main fishery parameters of brood Siberian sturgeon cultivated using the technology of intensive sturgeon aquaculture, which is not common in Ukraine, were studied. Practical value. The study results can be used for the development of modern methods of sturgeon aquaculture in the industrial farms conditions. Keywords: brood Siberian sturgeon, industrial fish farming, fishery parameters, ovulated eggs, combined aquaculture technology.

A simulation–optimization framework for reducing thermal pollution downstream of reservoirs

Abstract Thermal pollution is an environmental impact of large dams altering the natural temperature regime of downstream river ecosystems. The present study proposes a simulation–optimization framework to reduce thermal pollution downstream from reservoirs and tests it on a real-world case study. This framework attempts to simultaneously minimize the environmental impacts as well as losses to reservoir objectives for water supply. A hybrid machine-learning model is applied to simulate water temperature downstream of the reservoir under various operation scenarios. This model is shown to be robust and achieves acceptable predictive accuracy. The results of simulation–optimization indicate that the reservoir could be operated in such a way that the natural temperature regime is reasonably preserved to protect downstream habitats. Doing so, however, would result in significant trade-offs for reservoir storage and water supply objectives. Such trade-offs can undermine the benefits of reservoirs and need to be carefully considered in reservoir design and operation.

Impact of the natural temperature regime of the upper layers of Earth on efficiency of a hydrothermal heat pump system


 
 
 This article focuses on current issues of alternative geothermal heating development, by using low-potential thermal energy of upper aquifers by heat pumping technology. This type of heat supply is sustainable, does not require fossil fuel consumption and does not pollute the environment. In recent years, heat pumping technologies have become common. A lot of heating systems are implemented, using low potential energy in the air, open bodies of water or soil. Although, now, the heat of groundwater in upper aquifers is a more efficient and reliable source of energy for heat pumps. It was tested in this study. The purpose of this study is to impact assessment of the heat regime of the ground upper layers on efficiency of operation of heat pumping units, using groundwater of near-surface horizons. The factors founded, which form the natural heat mode within the studied area, also the correlation established between temperature changes in the horizon and the operation of the heat pump unit, based on the experimental heat pump unit, established by the Institute of Renewable Energy of the National Academy the Sciences of Ukraine. The article presents an experimental hydrothermal heat pump system developed and constructed at the Institute of Renewable Energy of the National Academy of Sciences of Ukraine, which consists of a heat pump and two wells through which water circulation from the underground horizon to the heat pump. The study describes the characteristics of measuring equipment installed on a hydrothermal heat pump system and described developed an interactive scheduling system based on the software product ESM (Engineering Systems Manager) using the programming language FBD (Function Block Diagram | Continuous Function Chart). This software product was used to create the visual system and archival data system that were obtained in the course of this work. The benefits of this study are that the experimental installation uses the thermal energy of groundwater of the Poltava-Kharkov aquifer as the primary energy source. The interval of the productive horizon is 32-57 m. The groundwater level in the horizon is set at about 40 m. In addition, the air temperature between the pipe space of the observation well and the groundwater temperature in the aquifer are monitored. The duration of regime observations was six months, the frequency of measurements – 5-15 seconds. The monitoring results indicate that despite the fact that the productive horizon is at a depth that significantly exceeds the usual depth of the neutral layer for the territory of Ukraine, the for- mation temperature is not stable and its amplitude is 2 oC. According to the authors, the increase in the depth of the surface of constant annual temperatures may be due to local features of the studied area, namely: increasing the absorption surface of solar radiation due to terrain, the presence of lateral heat inflow, the presence of water-saturated layers in the upper part. Consequently, based on the analysis of geological and hydrogeological conditions of the site, as well as technological processes occurring in the installation, the main factors that form the natural temperature of the upper layers of the earth are identified. As a result, the percentage of energy efficiency drop of the installation is calculated depending on the decrease in the temperature of the natural heat carrier in the aquifer. It is established that it is necessary to conduct additional research to assess the environmental impact of the use of aquifers for energy purposes and to ensure the optimal mode of operation of aquifers, which would be as close as possible to their natural regime.
 
 

Marbled crayfish Procambarus virginalis invades a nature reserve: how to stop further introductions?

We hereby provide the first documented data on the occurrence of a viable Procambarus virginalis population in a nature reserve in Poland and the steps that were taken to prevent further introductions of the species in the country. To date, Poland represents the most north-eastward distribution area in Europe, where the species occurs in ecosystems with natural water temperature regimes. The ecological plasticity of P. virginalis and its obligate parthenogenetic reproduction make this crayfish an exceptional invader. The crayfish may have detrimental effects on the native invertebrates, amphibians, and fish, and alter the state of the entire ecosystem. Therefore, we investigated the presence of the species in the nature reserve of Pojezierze Łęczyńskie Landscape Park after a suspected P. virginalis individual was found by a local citizen. The nature reserve also includes an area designated to protect native amphibians and turtles. Our study revealed the presence of a thriving population of P. virginalis in the protected area and clear indications of its impact on native and invasive species, both in aquatic and terrestrial environments. If no action is taken, the species will likely expand to other water bodies across the country. An extensive sensibilization campaign allowed us to find additional invaded areas and significantly contribute to the effective ban of this and other invasive crayfish species from private and commercial online trade. Raising public awareness and banning invasive crayfish species trade is essential for successfully detecting and preventing further introductions.

Економічна ефективність ікряного виробництва із використанням плідників сибірського осетра (Acipenser baerii Brandt, 1869), вирощених в індустріальних умовах

Purpose. To determine the main indicators of economic efficiency for artificially obtaining Siberian sturgeon ovulated eggs to the needs of commercial caviar production using brood stocks grown in floating cages in a reservoir with a natural temperature regime of the forest-steppe of Ukraine. Methodology. Calculations were made according to generally accepted methods in economics. For the economic analysis, the actual indicators of economic activity from the SRP “Osetr” LLC enterprise (Kyiv region) in the period 2020-2021 were used. The study was carried out for a fish farm with a capacity of 500 kg of Siberian sturgeon ovulated eggs in fish farm conditions and with the preservation of life of newly matured brood fish in 8+, 9+ and 10+ age groups. The structure of the analysed production costs with an assessment of the company’s profitability indicators provides for the implementation of processes with a full cycle for the cultivation and exploitation of Siberian sturgeon brood stocks with the combined use of modern methods in industrial aquaculture. Findings. In the cost structure of the analysed caviar production, the largest share is wages (30.21%) and costs for the purchase of feeds for different age groups of sturgeon (28.24%). It has been found that for the production of 500 kg of Siberian sturgeon ovulated eggs of brood stock from floating cages in reservoirs with a natural temperature regime and artificial production of mature eggs in recirculation aquaculture systems, the farm’s payback period is at least 10 years. The level of profitability for these type enterprises can exceed 26%. Ways to increase the profitability of these type fish farms with a reduction in the payback period of caviar production have been determined. Originality. For the first time, indicators of the economic efficiency in commercial sturgeon farming with the use of Siberian sturgeon breeding stocks and industrial technologies, which are not common for aquaculture in Ukraine, have been analysed. Practical Value. The study results can be used in the process of industrial aquaculture development and during the evaluation of the results from production activities in commercial caviar farming. Keywords: economic efficiency, industrial aquaculture, Siberian sturgeon, sturgeon caviar, combined technologies.

Досвід отримання зрілої ікри сибірського осетра (Acipenser baerii (Brandt, 1869)) у нетрадиційні рибницькі строки

Purpose. To investigate the peculiarities of obtaining ovulated eggs of the Siberian sturgeon in hatchery conditions in non-traditional (winter) period and determine major features of brood fish used for the experiments. Methodology. The material for the study were age-10+ Siberian sturgeon females with body weights of 6.20-8.24 kg grown in conditions of floating cages in a water body with natural temperature regime of the forest-steppe zone of Ukraine. The experiments were conducted with a regulated water temperature regime in the third decade of January with the use of natural gonadotropic drugs for the stimulation of egg maturation in fish. Brood fish were prepared for the experiment in the recirculating aquaculture system. Measurement of fisheries parameters and study of physicochemical factors of the aquatic medium were performed according to generally accepted methods. Experiment results were assessed statistically using standard software. Findings. With water temperature of 14-15оС, depending on the dosage of the gonadotropic drug, different efficiencies of gonad maturation in experimental groups of fish were detected. More than 85% of females matured after dosing of gonadotropic drugs 3.5 and 4.5 mg / kg. In the version with a minimum dose of gonadotropic substance 2.5 mg / kg responded positively to hormonal stimulation 57% of females. The average weight of eggs obtained in some groups of brood fish was 819.5-1079.0 g. Average working fecundity and relative working fecundity in experimental groups of the Siberian sturgeon females varied within 47.95-52.64 thousand eggs and 6.93-7.17 thousand eggs/kg of fish body weight, respectively. The duration of maturation after the second (resolving) administration of the gonadotropic drug until the moment of the occurrence of the ovulation process varied mainly within 15-20 hours. Originality. The peculiarities of obtaining mature eggs of the Siberian sturgeon with the use of methods of industrial reproduction of sturgeons, which are new for the aquaculture of Ukraine, were studied. Practical value. The study results are of interest for the development of modern methods of sturgeon aquaculture in conditions of fish farms of industrial type. Key words: brood Siberian sturgeon, industrial aquaculture, non-traditional technologies, eggs, ovulation, fisheries parameters.

Comparative analysis of muscle tissue amino acid composition of sturgeon breeded under natural and industrial conditions

The article presents comparative data on the chemical and amino acid analysis of the muscle tissue of sturgeons of the natural ichthyofauna of the Volgograd reservoir and those grown in a cage farm in the natural temperature regime of the 4th zone of fish farming in the Russian Federation using balanced feeding. The results obtained indicate the saturation of the muscle tissue of sturgeons consuming artificial feed with amino acids. The difference in nutrition is reflected in the biological value of meat. An important indicator of the biological value of a product is the qualitative and quantitative composition of muscle tissue amino acids. The natural nutrition of the Volgograd Reservoir does not fully satisfy the sturgeon’s need for protein nutrition. Industrial methods of cultivation make it possible to optimally organize biologically complete feeding of fish, which contributes to the maximum manifestation of their genetic potential and production of functional products.

Influence of experimental storage conditions of spores of Floating fern (Salvinia natans (L.) All., Salviniaceae Martinov) on the reproduction of the species

Salvinia natans is a heterospore annual aquatic fern from the Salviniaceae family. Increasing the spores’ viability by storage simulations is the basis for creating fern spore banks. In this aspect, S. natans appears to be an unconventional subject. Between October and August 2019–2020 we conducted an experiment on the storage of S. natans spore production for 4 months in 12 combinations of abiotic factors (lighting water content – temperature) and subsequent sporesgermination during the spring – summer under the same conditions of natural temperature regime, natural light and thepresence of water. The spore production viability was assessed by the time of megasporangia germination and the numberof new individuals in each storage option. We established that the of the S. natans reproduction occurs successfully witha natural combination of abiotic environmental factors – a gradually changing temperature with winter freezing, naturallight, and the presence of sporangia in water. Storage has a beneficial effect during stratification (+ 5 °C, water) and in thecombination of factors “natural temperature – dark – dry”. Early germination and the appearance of the maximum number of new individuals in these three wintering options indicate that S. natans adapts to the seasonal climate with low winter temperatures and warm summers. Dormancy of S. natans spores belongs to the forced type. Dry storage delayed germination of megasporangia for a period of two weeks to a month. The dormancy of S. natans spores belongs to the forcedtype, since the content of sporangia in water in the light and at room temperature showed the possibility of the appearanceof new individuals in October-November.

Surface water with more natural temperatures promotes physiological and endocrine changes in landlocked Atlantic salmon smolts

Hatchery salmonid smolts are often reared using groundwater with elevated temperatures to maximize growth. Previous work has shown that rearing hatchery smolts in surface water with a more natural thermal regime resulted in increased return rates of adult landlocked Atlantic salmon (Salmo salar). We evaluated whether landlocked Atlantic salmon reared in surface water with a natural temperature regime have altered physiological smolt characteristics compared with fish reared in groundwater with elevated winter temperatures. Hatchery fish were sampled three consecutive years from January to May. Additional fish were released as smolts, recaptured, and compared with fry-stocked smolts. Surface water smolts had earlier peaks of plasma T4, lower T3 levels, later peak cortisol, and lower gill Na+/K+-ATPase activity as compared with groundwater smolts. After release and recapture, surface water fish had elevated plasma T4 and gill Na+/K+-ATPase activity compared with groundwater fish, but less than stream-reared fish. Elevated plasma T4 in surface water fish in the hatchery and after release may have promoted imprinting and other aspects of smolt development, contributing to the higher adult return rates of a cohort reared in surface water.

Hydropower‐driven thermal changes, biological responses and mitigating measures in northern river systems

AbstractWater temperatures control life histories and diversity of aquatic species. Hydropower regulation, particularly in high head systems, alters natural water temperature regimes, which may have profound and long‐term impacts on aquatic environments. Temperatures in by‐pass sections and reaches affected by residual/environmental minimum flows fluctuate more than in natural flow regimes, driven more by influence of air temperatures. Reaches downstream of power plant outlets tend to become warmer in winter and colder in summer, driven by stratification behind the reservoir dam. In hydro‐peaked systems high‐low temperature effects may thus be aggravated. We review alterations of hydropower to natural thermal regimes, impacts on key organisms in terms of survival, development and behavioral thresholds, and potential mitigation measures, with focus on Atlantic salmon and brown trout in high northern latitude stream systems. Previous syntheses have focused mainly on flow changes and ecological impacts. Temperature effects may not always be correlated with flow changes, although there are some unique challenges with temperature changes in far northern latitudes, for example, related to the seasonal and colder climates. To help knowledge‐based management and identify potential knowledge gaps, we review how hydropower regulation may impact seasonal water temperatures, what impacts changes to stream system temperature regimes may have to key organisms, for example, Atlantic salmon and brown trout, and what adaptations and behavioral variations they may exhibit to respond to changed temperature regimes, and finally what good practices can be recommended for mitigating temperature impacts. This synthesis indicates that there are impacts to the fish and their supporting food webs, in particular related to growth and development, and the potential for negative impacts seems higher, and better studied, than positive impacts in northern river systems. Some of these impacts may be modified by directed hydropower regulation practices, but here effect studies and knowledge are limited.

First report of Scutariella japonica (Matjašič, 1990), a temnocephalid epibiont from South-East Asia, found on introduced ornamental freshwater shrimp in European waters

This contribution presents the first record of ornamental shrimp epibiont, Scutariella japonica (Platyhelminthes: Temnocephalida) in European waters. The species lives on freshwater Atyidae shrimp from temperate, subtropical and tropical zones of South-East Asia. In total, 120 individuals of Neocaridina davidi shrimp were caught in thermally polluted canal of Oder river, near the city of Gryfino, in the northwest part of Poland. In that group, 5.83% were infected with scutariellids. Among shrimp, females were mostly infected (85.71%). Since ornamental shrimp released into thermally polluted water bodies have been also noticed in surrounding waters of natural temperature regime in Europe, S. japonica may spread further following potential expansion of the Neocaridina shrimp in Oder river. It is possible that other crustaceans, both native and alien which are present at this location, may also become vectors of this epibiont.

Comparative characteristics of fishery indicators of various sturgeon species when grown in natural temperature regimes of water bodies of the Republic of Karelia

The paper presents materials on the rearing of Siberian sturgeon of the Lena population (Acipenser baerii Brandt), sterlet (Acipenser ruthenus Linnaeus) and their hybrid sturgeon (Acipenser baerii Brandt × Acipenser ruthenus Linnaeus) in the conditions of natural temperature regimes of natural reservoirs of the Republic of Karelia. It is noted that the climatic conditions of the region allow us to grow sturgeon to marketable sizes in cages in the natural temperature ranges of natural reservoirs. In order to determine the most suitable object for growing, the fish-breeding, biological and morphological indicators of Siberian sturgeon, sterlet and hybrid sturgeon were studied. The results of growing these objects in the cages of the Kedrosero fish hatchery showed their prospects for use in commercial fish farming. The highest indicators were observed when growing Siberian sturgeon, which showed a significantly higher rate of weight growth, good survival and effective use of feed. When grown for three years, the weight of Siberian sturgeon was 2053 g, sterlet — 682 g. The growth rate of the hybrid sturgeon was lower than that of the Siberian sturgeon and higher than that of the sterlet. The assessment of plasticity and exterior indices also showed the advantage of the Siberian sturgeon in comparison with other species. Fish-breeding, biological and morphometric indicators of sterlet and sturgeon hybrid were some lower, however, the high taste and nutritional value of these species make it possible to consider them quite promising objects of cultivation in the Northern regions.

Hummingbird torpor in context: duration, more than temperature, is the key to nighttime energy savings

Torpor is an important energy saving strategy in some small birds, but it has rarely been studied in natural field conditions. We compared torpor use across 43 wild‐caught individuals of eight hummingbird species across sites with different natural temperature regimes. Most laboratory studies focus on the relationship between metabolic rate and temperature, but our aim was to evaluate what environmental factors most influence hummingbird nighttime energy management under natural conditions. We found that the probability of an individual entering torpor was weakly correlated with mass but unrelated to nighttime temperature and that hummingbirds at both warm, tropical and cooler, temperate sites used torpor. Energy savings in torpor were maximized as ambient temperatures approached a species’ minimum body temperature, consistent with laboratory studies; energy savings ranged between 65 and 92% of energy per hour in torpor compared to normothermy. However, regardless of the degree of energy savings in torpor, variation in total nighttime energy expenditure was most significantly influenced by torpor bout duration. Lab studies largely assess the effect of temperature on torpor use, but our findings indicate that other environmental conditions are more important in determining hummingbirds’ total nighttime energy expenditure under natural temperature cycles. Our results show that a small endotherm's nighttime energy management in its natural habitat is more affected by torpor bout duration, which is linked to photoperiod, than by temperature. This result suggests that in their natural environments hummingbirds are able to save energy in torpor across a range of nighttime temperatures, indicating that they may have sufficient physiological flexibility to tolerate climatic variation.

Determination of the optimal step of installation between the evaporator pipes and the number of condenser units of the system of temperature stabilization of soils HET

Interest in developing the resource base of the Arctic and subarctic regions has recently increased thanks to the efforts of the media, oil corporations and the government, however, it must be understood that during the construction on the soils of these regions, in which ice acts as a cementing material, their natural temperature regime is violated. leading to the melting of the ice phase. It is known that when thawing frozen soil it loses its strength properties, as a result of which the foundations of the structures on which they are built are at risk of deformation and destruction. To solve this problem, special devices have been developed - seasonally acting cooling devices (SOU), which cool the soil in the cold season and "lock up" in the warm. For this reason, these devices are also called "thermal diodes." In this work, we consider the system of temperature stabilization of soils HET (horizontal naturally acting tubular system) installed at the base of a vertical steel tank (PBC) filled with hot oil-water mixture. A system is considered, in which ammonia acts as a coolant. In addition, the article carried out calculations of various design solutions of the HET system, expressed in variations of such parameters as the length of the evaporator, the number of condensers, and the installation step between the pipes of the evaporator. The work raises the question of justifying the laying step between the pipes of the HET system evaporator and the number of condenser blocks that will be sufficient for the effective functioning of the system, i.e., to maintain the soil in a frozen state. It is shown that for the effective functioning of the system it is not necessary to use a standard paving step equal to 0.5 m, but it can be increased without the risk of losing the bearing capacity of frozen soil. One of the results of the work is the fact that the system is overdetermined by the temperature of stabilization of soils of the HET type at small distances of the laying step relative to the increased distance, which is expressed in a decrease in the number of working days during a calendar year, all other things being equal.

Effect of Gonadotropin Releasing Hormone Injection on Physiological Changes and Reproductive Hormones in Clarias gariepinus

Evaluation of gonadotropin releasing hormone (GnRH) to physiological changes, spawning and reproductive parameters of African catfish, Clarias gariepinus in the current study has been conducted to determine the effectiveness of GnRH in stimulation the maturation and ovulation of African catfish. GnRH at 4, 8 and 12 μg/kg body weight dissolved in 0.6% NaCl under a natural temperature regime. The fish from Abbasa farm were fed with 30 % protein diet during experiment. Fish550 - 600 g body weight were injected with a doses of (4, 8 and 12 μg/kg body weight) three times a week. Result showed multiple ovulations and spawns within a period of approximately 30 days. Levels of 17β- estradiol (E2), testosterone (T) and follicular stimulating hormone (FSH) were elevated at 30 days’ post treatment, preceding the spawns with the highest fecundity. These results show that administration of GnRH induces multiple spawns in fishwhere, approximately 100% increase in red blood cells (RBCs), white blood cells (WBCs), hematocrit value (Hc) and hemoglobin content (Hb) respectively. Also, there are increased in plasma glucose level, total protein, aspartate and alanine amino transferase activities (AST and ALT) and increased in plasma creatinine and uric acid concentration after administration of GnRH. These data suggest that fish respond to administration of GnRH by increasing their hematology, enzymes of liver functions and kidneyfunctions. Injection of GnRH at 4, 8 and 12 µg/kg was found to be effective to induce ovulation in African catfish. 100% ovulation was also observed for the fish treated with GnRH. Also, plasma level of E2, FSH and T increased significantly with the association of ovulation. The present study indicates that administration of GnRH is effective for sexual maturation and ovulation in African catfish.

Maintaining thermal stability of a fill slope in cryolithozone

The paper describes a solution to the problem of maintain the stability of a fill slope through artificial freezing with seasonal cooling units in cryolithozone. A three-dimensional mathematical model was developed to calculate the heat flow in a fill slope reinfirced with a gabion wall, taking into account the liquid-liquid phase transition and the use of seasonally operating cooling units. The developed mathematical model, based on the finite difference method and implemented as an application for Microsoft Windows, allows making a long-term forecast of a temperature field in a fill slope, depending on various design and technological parameters (location, dimensions and an operating mode of thermal stabilizers) and its effect on the stability of the slope. The results of studying the contribution of thermal stabilization to a reduced destructive temperature effect of the environment on the slope are given. The study showed the effectiveness of using seasonal cooling units for increasing the stability of fill slopes by freezing. In subsequent years after the thermal stabilization, the frozen zone in the fill slope is preserved, with the slope gradually switching to the natural seasonal temperature regime. The paper is recommended for researchers and designing engineers dealing with applied issues of mining thermal physics.

Продуктивність сортів і гібридів кукурудзи за різних систем удобрення та беззмінного їх вирощування

The purpose. To carry out the impact analysis of anthropogenic (one-crop system, system of fertilizing, grade, hybrid) and natural (temperature and water regimes) factors on productivity of corn and dynamics of elements of soil fertility in conditions of Left-bank Forest-steppe of Ukraine. Methods. Field, statistical, laboratory. Results. Results are given of long-term researches in growing corn for grain in permanent sowing (one-crop system) and as thus under impact of fertilizing its productivity and soil fertility varied. As a result of agrochemical analysis of soil samples it is fixed that on fertilized plots the content of gross and mobile forms of nutrients was higher, than on not fertilized (control). At the same time irrespective of system of fertilizing the yielded indexes were dynamical on soil profile. In structure of biological groups of weeds late spring made 59–64%, early spring — 21–27, perennial — 13,9%. Conclusions. As a result of researches in typical chernozem in conditions of Left-bank Forest-steppe of Ukraine it has been fixed that anthropogenic and natural factors differently influence the level of productivity of corn for grain and soil fertility at its growing in one-crop system. Thus, productivity of the crop more depends on weather and less — on duration of growing in one place. At mathematical analysis of the gained results of researches in productivity of corn and dependence of its magnitude on fertilizer system, temperature and water regimes it has been fixed that their correlation envelopes a wide spectrum - from straight up to inverse. The carried out account of weeds has shown that on the average for 4 years of researches for 1 m2 of one-crop sowing their amount made 84,9 pieces/m2, whereas in crop rotation — 59,1 pieces/m2, that on 30% is less.

Seasonal reversible size changes in the braincase and mass of common shrews are flexibly modified by environmental conditions

The growth of the vertebrate skull and brain is usually unidirectional and more or less stops when animals are adult. Red-toothed shrews break this rule. They seasonally shrink and regrow brain and skull size by 20% or more, presumably to save energy when conditions are harsh. The size change is anticipatory of environmental change and occurs in all individuals, but it is unknown whether its extent can be modulated by environmental conditions. We kept shrews under different conditions, monitored seasonal changes in skull size with series of X-rays, and compared them with free ranging animals. We found extensive differences in the pattern of skull size change between experimental groups. Skull size of shrews kept at constant temperature showed a steady decline, while the skull size changes of free ranging shrews and captive individuals exposed to natural temperature regimes were identical. In contrast, body mass never reached the spring values of free ranging shrews in either captive regime. The extent of this adaptive seasonal pattern can thus be flexibly adapted to current environmental conditions. Combining reversible size changes with such strong phenotypic plasticity may allow these small, non-hibernating predators with high metabolic rates to continue being successful in today’s changing environments.

Результати штучного відтворення осетрових риб, вирощених у садках за природного температурного режиму водойм лісостепової зони України

Результати штучного відтворення осетрових риб, вирощених у садках за природного температурного режиму водойм лісостепової зони України